import java.util.*;

public class Text2 {
    public List<String> topKFrequent(String[] words, int k) {



        //1、统计每个单词出现的次数
        Map<String,Integer> map = new HashMap<>();
        for (String word : words) {
            if(map.get(word) == null) {
                map.put(word,1);
            }else {
                int val = map.get(word);
                map.put(word,val+1);
            }
        }


        //2、建立小根堆,指定比较的方式
        PriorityQueue<Map.Entry<String,Integer>> minHeap = new PriorityQueue<>
                (new Comparator<Map.Entry<String, Integer>>() {
                    @Override
                    public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {

                        if(o1.getValue().compareTo(o2.getValue()) == 0) {
                            //按照字母顺序建立大根堆
                            return o2.getKey().compareTo(o1.getKey());
                        }

                        return o1.getValue()-o2.getValue();
                    }
                });

        //3、遍历map 调整优先级队列

        for(Map.Entry<String,Integer> entry: map.entrySet()) {
            if(minHeap.size() < k) {
                minHeap.offer(entry);
            }else {
                Map.Entry<String,Integer> top = minHeap.peek();
                //如果当前频率相同
                if(top.getValue().compareTo(entry.getValue()) == 0) {
                    // 字母顺序小的进来
                    if(top.getKey().compareTo(entry.getKey()) > 0) {
                        //出队
                        minHeap.poll();
                        minHeap.offer(entry);
                    }
                }else {
                    if(top.getValue().compareTo(entry.getValue()) < 0) {
                        minHeap.poll();
                        minHeap.offer(entry);
                    }
                }
            }
        }

        List<String> ret = new ArrayList<>();
        for (int i = 0; i < k; i++) {
            Map.Entry<String,Integer> top  = minHeap.poll();
            ret.add(top.getKey());
        }

        Collections.reverse(ret);

        return ret;

    }
}
